Project Summary/Abstract The long-term aim of this project is to understand the effect of age on speech recognition in coch- lear-implant (CI) users. The specific objective of the proposed research is to investigate basic measures of auditory temporal processing in older CI users to establish age-related temporal processing deficits. The proposed experiments are designed to measure psychophysical tem- poral processing ability in younger and older CI users. Aim 1 will measure single-electrode gap detection ability at different carrier pulse rates. This study will test the hypothesis that older CI users will display poorer performance on simple, non-speech temporal processing tasks, espe- cially at fast carrier rates. Aim 2 will measure single-electrode amplitude-modulation (AM) detec- tion ability at different carrier pulse rates. This study will test the hypothesis that older CI users will require larger depths of modulation for detection compared to younger CI users, particularly at fast carrier rates. Electrophysiological responses (electrically evoked compound action poten- tials [ECAPs]) will also be measured in both aims to investigate the contribution of peripheral neural survival, which could otherwise confound the effect of age alone, on central auditory tem- poral processing ability. The training program involves extensive instruction in digit signal pro- cessing and advanced statistical analysis relevant to the proposed research. The results from the proposed project will expand the understanding of potential sources of individual variability in CI outcomes, particularly for older CI users. This knowledge will help to develop improved CI pro- gramming techniques for CI users with auditory temporal processing deficits.